Dental flasks



Oct. 16, 1962 s. HARRIS 3,058,155

DENTAL FLASKS Filed Deo. l, 1959 `SAMUE L HARRIS A RNE Y United States Patent C) 3,058,155 DENTAL FLASKS Samuel Harris, 94-15 69th Ave., Forest Hills, N.Y. Filed Dec. 1, 1959, Ser. No. 856,405 1 Claim. (Cl. 18-33) This invention relates to dental flasks wherein artificial dentures are formed and more particularly to a three member hinged molding flask that is especially adapted for processing acrylic teeth to extensive metal bridgework or for processing acrylic teeth to a plate member.

The present invention is an improvement to the dental flask disclosed in my earlier patent, No. 2,896,259. In the flask therein disclosed, there is provided a shell-like base member Ithat accommodates a convex platform piece over which investment material is molded. A metal bridge having wax teeth formed thereon in the places where acrylic teeth are ultimately to be provided is arched over, and ern-bedded, in the convex surface of the investment material. An upper flask member hinged to one end of the base member is filled with investment material whereupon it is pivoted into engagement with one-half of the bridgework embedded in the investment material formed on the platform. A second upper flask member hinged to the other end of the base member is similarly filled with investment material and pivoted into engagement with the other half of the embedded bridgework. A clamping device is then utilized to bring the three members of the flask into intimate and tight contact with each other. After the investment material has hardened and the flask opened, an impression of the wax teeth is formed in the investment material of the upper flask members. The wax can then be melted from the bridgework and a mold is thus provided into which the acrylic material is placed. By reclosing and tightening the flask with the clamping device, the acrylic material in the form of teeth conforming to the pattern of the mold, is adhered to the metal bridgework.

The flask of the earlier patent has many advantages, one of which is that the acrylic material may be readily viewed lby the dental technician as he reopens and recloses the flask, and hence the coloring and shading of the dentures can be altered during the process of forming the teeth. Another advantage of the flask is that a locking member is provided which insures that a finished dental bridge will faithfully conform to the shape and size of the wax yteeth used in making the mold for the acrylic teeth.

It has been found that further improvements can be made to the three member hinged dental flask of my earlier invention, particularly with regard to the clamping device used to press the three flask members into close contact with each other. It is extremely imporatnt that the three members be tightly engaged so that the acrylic material placed in the mold fill all the voids thereof yand in addition be as dense as possible. This requires that the clamping device be capable of exerting great pressures in forcing the flask members into ntimate engagement.

In carrying out the present invention there is provided a pair of presses each of which applies a force to direct an upper flask member into engagement with the base member of the flask. Each press is capable of being self-supporting in an upright position so as to facilitate its use by the dental technician. Moreover, the press is such that it applies a force in a direction most efficient in bringing the flask members into tight contact with each other.

Features and advantages of this invention will be gained from the foregoing and the description of a preferred embodiment thereof which follows.

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In the drawings:

FIGURE l is a front elevational view, partly in section, showing a three member hinged dental flask, employing a press for clamping the flask; and

FIGURE 2 is a sectional View taken along line 2-2 of FIGURE l.

Referring to the drawings, a base flask member 10 is shown having a central cavity 11 of generally rectangular form and a size to accommodate a removable platform piece 12. The platform piece comprises a base portion 13 that fits substatnially into cavity 11, and an upper convex portion 14. The upper convex portion is shown extending between the sidewall members 15 as it would be in the event that a dental bridge was being molded. However, if a full dental plate was being made the convex portion 14 would take the form of two spaced apart upright members. A cover piece 20 is also provided to fit over the platform 12. While platform 12 itself may be used effectively, the provision of cover piece 20 has been found useful to insure the production of good fitting dental bridges. This for the reason that the dental bridge is a very delicate structural element that can too easily be deformed in removing it from the investment material in which it is embedded. It is obvious Ithat even the slightest spring of the bridgework will result in a misfit when placing such bridge in the mouth of a patent. With the provision of the cover piece 20 the routine work of forming a dental bridge can be performed by the less skillful workers in a dental laboratory. Thereafter, the finished bridge can be removed from the flask by removing the platform and sliding cover piece 20 from the platform. The flask can then immediately be put to further use by utilizing an additional cover piece 20 while the bridgework formed can be removed from the original cover piece at the convenience of the most skillful technician in the laboratory.

An aperture 19 formed in the bottom of base member 1t) is provided so that platform piece 12 containing hardened investment material and the finished bridge may be readily removed from member 10 after the bridge making operation is completed as by tapping the bottom of piece 12 through the aperture with an appropriate tool.

The side wall members 15 are formed integral with base member 10. 'Of course, such members may be removably fastened to base member 10 as by interlocking pins provided on the side walls and projecting into approximately placed holes in the base member as in my earlier patent. With the platform piece in place, the upper convex member 14 abuts the side walls 1S. Locking segments 17 are formed integrally on the side walls and they perform the same function as member 17 with prongs 22 of my earlier patent. It has been found that the integral construction of the flask as herein described has greatly simplified the flask so as to render it more easily useable by dental technicians.

One end of base member 10 is formed with a pair of projecting arms 23 which serve to support a pin 24. A hook-like appurtenance 25 formed on upper flask member 26 engages the pin in the fashion of a hinge so that the flask member 26 can be pivoted thereabout. Member 26 is also formed with walls 27 which when the member is in closed position conform to the contour of the side walls 15. A U-shaped lug 30 formed atop member 26 may be utilized to lock the flask as will hereinafter be described. An aperture 29 is provided in the upper flask member to facilitate the removal of hardened investment material therefrom after the flask has been used.

The other end of base member 10 is similarly provided with a pair of projecting arms 3'1 which serve to support pin 32. A hook-like appurtenance 33 formed on the second upper flask member 34 engages pin 32 so that flask member 34 can be pivoted thereabout to a closed position. When in such position, the walls 35 of member 34 conform to the contour of side walls 15. As in the case of member 26, member 34 also is formed with a U-shaped lug 36. An aperture 37 is provided in flask member 34 to facilitate the removal of hardened investment material therefrom after the flask has been used.

A clamping device is provided for forcing the three flask members into intimate engagement with each other and for locking the thus engaged members into a rigid assembly. The clamping device comprises, preferably, a pair of presses which are identical in construction so that only one need be described. The press has a frame 40 containing a pair of upright members 41 which are spaced apart a distance sufficient to span the flask as shown in FIGURE 2. As seen in FIGURE l when the press is in position on the flask, -the upright members 41 are canted away from the center of the flask. The reason for this is so that the pressure applying platen 42 can engage an upper flask member obliquely and thereby force the upper flask member both towards the other upper flask member and towards the base member rather than towards the other upper flask member alone as in my hereinabove referred to patent. The base portion 43 of the press is enlarged so that even though the upright members are canted rearwardly, the press will be capable of standing on a horizontal surface. The upper cross member 44 joining upright members 41 is provided with an internally threaded aperture 45 through which passes the threaded stud 46 to which is rotatably secured platen 42. The upper end of the stud is provided with a handle 47 whereby the stud may be rotated and pressure applied to platen 42. After a press as herein described is used to tighten the flask and bring the flask members into intimate engagement, the press may be removed and a clamping device as described in Patent 2,896,259 may be used to lock the flask members together during the curing process.

In operation, the platform 12 is placed in the base flask member and between the sidewalls 15 thereof. Investment material in plastic form is then a bed on which the dental bridge is added until it is in line with the top of the side member so that the edges 17 of member 17 project well above the material. A metal bridge or denture having a full plate is then embedded in the investment material with the wax teeth formed thereon aligned with the surface of the investment material which is then permitted to harden. Thereafter, investment material in plastic form is placed in one upper flask member which is then swung into engagement with the wax teeth pattern so that an impression of the outer surface of the teeth is formed in the investment material. The edges 17 of sidewalls 15 extend into the material so that after the material hardens there can be no lateral shifting, between the upper and the lower flask members. Next, the other flask member is filled with soft investment material and it is swung into engagement with the remainder of the flask, so that the wax teeth pattern forms a mold in the material. The clamping device is then employed to lock the three flask members into a rigid assembly. Since the ridges 17 of sidewalls 15 extend into the material of the second upper flask member, there can be no lateral shifting of this piece with respect to the bottom member. After the investment material hardens, the mold is completed and the flask may be opened and the wax removed from the metal bridge, as by placing the flask in boiling water. The acrylic material used to form the teeth of the dental bridge is then placed in the mold cavity and the flask is locked up with the presses. The acrylic material is then cured to secure its integration with the metal bridge. Thereafter, investment material in which the completed bridgework is embedded is removed from the flask and the bridgework is dislodged by tapping the hardened investment material with a suitable tool.

Inasmuch as many apparently different embodiments of the invention can be made without departing from its spirit or scope, it is intended that what has been shown in the drawings and described in the specification be interpreted as illustrative and not in a limiting sense.

What is claimed is:

A clamping device for use with a three member hinged dental flask having a base member with upstanding sidewall elements, a flrst arcuate upper flask member pivotally connected to one end of said base member and swingable into cooperative relationship with half of said sidewall elements and a second arcuate upper flask member pivotally connected to the other end of said base member and swingable into cooperative relationship with the other Ihalf of said sidewall elements, said clamping device comprising a lower cross member, a pair of spaced apart upright members extending upwardly from said lower cross member, said upright members being spaced apart a distance sufllcient to permit the dental flask to fit therebetween, an upper cross member joining the top ends of said upright members, said upper cross member having a threaded aperture provided therein, a threaded stud cooperating with and extending through said threaded aperture, a platen rotatably fastened to the lower end of said stud for engaging an upper flask member, andV handle means secured to the opposite end of said stud whereby the stud may be rotated to place pressure on a flask inserted in the clamping device characterized in that said upright members are canted rearwardly so that when the threaded stud is rotated to place pressure on the flask the pressure is applied diagonally to urge the upper flask member about its pivot and the lower cross member has an enlarged base extending below the upper parts of the clamping device so that said device is self supporting in an upright position.

References Cited in the ille of this patent UNITED STATES PATENTS 546,465 Griswold Sept. 17, 1895 565,326 Bragg Aug. 4, 1896 584,839 Andrews June 22, 1897 722,726 Lewis Mar. 17, 1903 2,453,303 Cline Nov. 9, 1948 2,858,568 Myerson Nov. 4, 1958 2,896,259 Harris July 28, 1959 

